Refrigerating apparatus and means for lubricating same



1933 H. c. KELLOGG ET AL L8 9 REFRIGERATING APPARATUS AND MEANS FORLUBRICATING SAME Filed March 30, 1929 2 Sheets-Sheet J.

1932' H. c. KELLOGG ET AL 1,885,337

REFRIGERATING APPARATUS AND MEANS FOR LUBRICATING SAME Filed March 50,1929 2 Sheets-Sheet 2 wwwwfia' /WC KW AWA/EK Patented Nov. 1, 1932 IUNITED MRBEBT G. KELLOGG AND EDWARD ELMAY, F DETROIT, MICHIGAN,ASSIGNOBS T0 GLEN 1. COWAN, 0F DETROIT, MICHIGAN; GRACE A. COWANEXECUTBIK OF SAD GLEN P. OOWAN, DZEKEEASIEZD-v BEFBIGERATING APP was am)as For. nunnrcarme same Application filed March 80, 1329. Serial No.351,372.

This invention relates to refrigerating apparatus in which a gaseousrefrigerating fluid is cyclically condensed and liquefied and againevaporated from the liquid to the gaseous state with the accompanyingabsorption of heat. The improvements have to do more particularly withthe means or apparatus for evaporating the liquid refrigerant to thegaseous state and to the relations of that apparatus to the means bywhich the refrigerant is condensed and liquefied. The applicationconstitutes a continuation in part of our copending application SerialNo. 295,- 174, filed July 25, 1928, in which we claim the heroindisclosed means for returning at least some extent, soluble in theliquid refrigerant employed and having improved means for maintaining asuitable body of liquid refrigerant in the evaporator and returningaccumulated lubricant from the "evaporator to the refrigerant pump or.condenser.

Another object of the invention is the provision of a refrigeratingapparatus employing an evaporator of the flooded type and-a re rigerantin which the liquid lubricant is more or less soluble, which is adaptedunder varying heat loads, i. e. varying rates of heat transfer, tomaintain the lubricant in the evaporator at a relatively small andconstant amount and at the same time to revent discharge of refrigerantin the liqui state from the evaporator to the compressor.

A further object of the invention is the provision of an evaporator ofthe flooded type having an improved float valve for con trolling theadmission of liquid refrigerant to the evaporator, the valve mechanism,in-

Another object of the invention is the prov vision of an improved methodof lubricating the working parts of mechanical refrigerating apparatusof the type employing afiooded evaporator.

. Other objects of the invention more or less incidental or ancillar tothe foregoing will appear in the following description setting forthsome of the preferred forms of construction and methods of carrying outthe infrigeration apparatus embodying the inven- .5

tion, the invention being shown in conjunc tion with a refrigerator ofthe domestic type.

Fig. 2 is an enlarged section on the line 22, Fig. 1, showing thecooling unit of the refrigerator with the tray of the brine tankremoved.

Fig. 3 is a section on the line 3-3, Fig. 2. Fig. 4 is a verticalsection through an evaporator of modified construction adapted for usein lieu of that illustrated in Figs. 1 to 3.

Fig. 5 is a section on the line 5-5, Fig. 4;-

Referring in detail to the construction illustrated, and first to theform of apparatus illustrated in Figs. 1, 2 and 3,- 1 designates as anentirety an evaporator of the flooded type which is associated with abrine tank 2 to form a cooling unit which is shown mounted in the usualmanner in a refrigerator 3 of the household type. 4 is a refrigerantcompressor which ma be of any suitable known form of constructlon and 5is an electric motor by which the compressor is driven through a belt 6.7 is a condenser which may be cooled by water circulation or in anyother known manner. A pipe or conduit 8 connects the inlet or suctionopening of the compressor 4 with the discharge passage of the evaporator1; a conduit 9 connects the discharge passage of the compressor with thecondenser 7 and a conduit connects the condenser 7 with the inlet of theevaporator 1. The operation of the compressor in apparatus of thischaracter is usually intermittent and in the construction illustrated itis controlled by an automatic switch 11 which may be of any suitableknown construction and which is actuated by the pressure of the gaseousrefrigerant in the suction conduit 8 with which the switch 11communicates through a conduit 12. 13 is the usual manual switch forthrowing the entire apparatus into or out of operation.

The present invention has to do particularly with the construction andfunctioning of the evaporator 1. In the construction illustrated inFigs. 1, 2 and 3, the evaporator 1 comprises a shell 14 made of twosections 14 and 14 of sheet metal which are stamped or drawn into theroughly oval or elliptical form shown in Fig. 3 and which are joinedtogether by the horizontal flanged seam 15- which is brazed or solderedto render the joint gas tight. The top wall of the shell is formed withan opening in which is hermetically secured a fitting 16-to receive athreaded refrigerant inlet tube 17 which depends within the evaporator.The oint between the tube 17 and the fitting 16 is rendered gas tight 4by a washer or gasket 17 c of soft metal or other suitable materialwhich is clamped between the fitting 16 and a shoulder formed by thehead 17 a of the tube 17. The said head 17 is formed with a threadedhorizontal opening 17 to receive the end of the refrigerant conduit 10.

A valve to control the passage through the inlet tube 17 is' secured tothe lower end i of the said tube. The valve comprises a body member 18which fits nicely within the lower end of the tube 17 and is formed witha shoulder 18 to engage the lower end of said tube. The valve body 18 isformed with an axial passage having an upper part ofone diameter and alower part of larger diameter so as to form intermediate its ends a seatfor a needle valve 19 whi h is preferably formed from stockapproximately triangular in cross section and has a depending stem 19*of reduced, diameter. A flanged and threaded fitting 20 engages thethreaded lower end of the tube 17 and servesto secure the valve body 18tightly in position in the lower end of the tube and also secures theneedle valve 19 in the valve body, with the stem 19 of the valveprojecting downward through a hole in the lower end of the fitting 20,said hole being larger than the stem so that liquid flowing through thetube 17 and passing the valve 19 has free outlet through the lower endof the fitt ng 20. The upper end of the valve body 18 has a reducedextension or nipple to which is secured a tubular metal gauze filter 21.

, S urrounding the depending tube 17 is an inverted annular cup-shapedfloat 22 provided with a central tubular part 22*. v This float has ametal strip 22 secured to the lower end of its cylindrical tubular part22*, so as to engage the stem 19 of the valve proper and is dischargeamas-av press the valve against its seat when the float is lifted.

The upper wall of the shell 14 has a second opening to receive a fitting23 which carries a depending discharge tube 24 and an elbow 24 which isconnected to the suction conduit 8 leading to the compressor. Below thefitting 23 is an open-topped receptacle 25 which is roughly crescentshape or kidney shape in horizontal outline and which is suspended fromthe fitting 23 by a support 26, the position of the receptacle 25 beingsuch that the lower end of the tube 24 is somewhat above the bottom ofthe receptacle.

The evaporator shell contains a body 27 of liquid refrigerant or, morestrictly speaking, combined refrigerant and lubricant. The open bottomside of the float 22 is submerged in the liquid refrigerant, or combinedrefrigerant and lubricant and, with gas trapped in the float, the latterhas ample buoyancy. With the accumulation of pressure in the evaporatorshell the liquid therein tends to rise in the float cavity above thebottom edge of the float but not to as high a level as the liquidattains outside of the float. In the operation of the apparatus someevaporation of the liquid refrigerant always occurs directly beneath thefloat and some of the gaseous refrigerant thus formed finds its wayupward into the chamber of the float thus assuring adequate buoyancy atall times.

In the construction illustrated, the evaporator shell-14 is mounted inthe top wall of a brine tank 28 with the lower part of the evaporatorshell submerged in the brine in said tank, the brine tank being indetail of any suitable construction. As shown it. is provided with areentrant chamber to receive a tray 28- for freezing water or foods.

The evaporator, as well as the other parts of the apparatus, is adaptedfor the use of various refrigerants among which may be mentioned by wayof example sulphur dioxide, methyl chloride and ethyl chloride.

Lubricating oils which are suitable for the lubrication of thecompressor are more or less soluble in most if not all of the preferredand commonly used refrigerants such as those mentioned. Thussuitablemineral oil lubricants are partially soluble in sulphur dioxideand are completelysoluble in methyl chloride and ethyl chloride, atleast within 1 the limits of the proportions of oil and refrigerantnormally employed. On account of this solubility, the liquid lubricantwhich is'scrubbed ast the compressor piston and (i into the condenser,dissolves in the refrigerant liquefied in the condenser and passes withthe latter in' solution into the evaporator. Then when the refrigerantis evaporated'the oil is left and accumulated in the evaporator so thatprovision must be made for its return to the compressor.

Assuming that the apparatus has been assembled and a suitable amount ofrefrigerant, such for example as sulphur dioxide, together with asuitable amount of lubricant, such for example as a suitable mineraloil, have suitably charged into the system, the operation of theapparatus is as follows. Heat absorbed through the wall of theevaporator causes evaporation of liquid refrigerant therein withresultant rise of the pressure in the evaporator and in the return orsuction conduit 8, which rise in turn causes the operation of the switch11 to close the electric circuit and start the operation of thecompressor 4. The compressor draws the gaseous refrigerant from theevaporator thus reducing the pressure therein and increasing the rate ofevaporation of the liquid refrigerant in the evaporator. When the levelofthe l quid in the evaporator falls as a result of the evaporation, thefloat 22 is lowered and the valve 19 permitted to move away from itsseat and admit additional liquid refrigerant, the float thus serving toau tomatically maintain a nearly constant amount of liquid in theevaporator. The evaporation is, of course, accompanied by the usualcoolin effect upon the evaporator and the surroun ing space cooled byit, which in the case illustrated is the brine tank and the interiorspace of the refrigerator 3. As the temperature of the evaporator islowered by the operation of the compressor the pressure in theevaporator is also correspondingly lowered and when the pressure reachesa predetermined point the switch 11 is opened to stop the operation ofthe compressor. The operation thus described constitutes the usual cycleof operations of apparatus of this general character. 7

However, the detailed operation within the evaporator during the cycleis quite distinctive and, as far as we are aware, peculiar to ourimproved form of apparatus. When the operafion of the compressor isstarted it begins at once to reduce the pressure in the evaporator withresultant starting of relatively rapid evaporation within the mass ofthe liquid refrigerant in the evaporator. lhis evaporation isaccompanied by the formation of bubbles of gaseous refrigerant withinthe mass of the refrigerant which have the efl'ect of raising thelevel'of the liquid in the evaporator, this eflect being most marked atthe beginning of the operation of the compressor because it takes anappreciable amount of time for the bubbles formed in the lower part ofthe mass of refrigerant to rise through the liquid and escape from itsupper surface. Consequently when the compressor is started the level ofthe liquid in the liquid when refrigeration is not going on, but thehighest parts of the agitated surface of the liquid remain considerablyabove the said normal level; The temporary rise of the level of theboiling liquid to a maximum height before the gaseous refrigerant beginsto escape from the surface of the liquid is naturally more marked wherethe depth of the body of liquid refrigerant in the evaporator isrelatively great so that a longer interval of time is required for thegas formed in the lower part of the body of liquid to rise through saidbody and escape from its upper surface. The float 22 is designed tomaintain a normal level of the liquid in the evaporator at such adistance below the top edge of the receptacle 25 that theincrease in thevolume of the boiling liquid at the beginning of the operation of thecompressor will carry the level of the liquid up nearly to or evensomewhat above the said top edge or rim of the receptacle 25. When thelevel of the liquid is thus carried above the rim of the receptacle itis clear that some'of the liquid will spill over into the float and bedrawn through the tube 24 and suction conduit 8 back to the compressor.This latter action is more particularly feasible and de sirable when arefrigerant is employed in which the lubricant is only partially solubleand which is of a greater specific gravity than the lubricant so thatthe excess lubricant accumulating in the evaporatorrises and forms adistinct stratum at the top of the body of liquid so that 011 onlyspills over into" the float on the temporary rise of the liquid level asabove described. By properly fixing the height of the rim of thereceptacle 25 above the normal liquid level (that is the level whenevaporation is not goingon), for a given depth of liquid refrigerant in'the evaporator and a given heat load, the rise of the liquidrefrigerant nnderlyingthe stratum of lubricant to a level above the rimof the receptacle is avoided while onlyexcess lubricant accumulated inthe'evaporator is discharged into the receptacle and returned to thecompressor in the manner described. When a refrigerant and a lubricantare used that are mutually soluble in all usable proportions thereof, itis preferable that the maximum liquid level attained be somewhat belowthe rim of the receptacle 25. Whether the maximum liquid level be aboveor somewhat below the rim of the receptacle. a discharge of lubricantinto the receptacle and thence back to the vcompressor is attained in amanner which will now be explained.

Assuming, for example; that the refrigerant is sulphur dioxide and thatthe lubricant is a suitable mineral oil of lower specific gravity thanthe liquid refrigerant, with the normal liquid level in the vaporizerchamber 14 somewhat above the middle of the float,

as indicated in Fig. 2, when the compressor is started and evaporationbegins in the evaporator, if the float has been designed to secureoverflow of lubricant into the receptacle 25, the increase in volume ofthe liquid in the evaporator due to submerged bubbles will raise theliquid levelv temporarily slightly above the rim of the receptacle sothat some of the stratum of oil floating on the liquid S0 will flow intothe receptacle and be drawn by the suction of the compressor-through thetube 24 and conduit 8 back to the compressor, as previously described.Then as soon as the bubbles of gasified refrigerant begin to breakthrough the surface of the liquid, the average level of the liquid willfall again approximately to the normal level indicated in Fig. 2, thoughby reason of the agitation of the liquid the uppermost surface thereofattains somewhat higher levels. Thereafter, as, evaporation continues,the bubbles of gasified refrigerant break through the surface of theliquid forming a mass of bubbles or foam which may build up until itrises above the rim of the receptacle, whereupon some of it is carriedover into the receptacle from which it is drawn by the suction of thecompressor.

When the liquid refrigerant and the lubricant employed are completelymutually soluble, as where methyl chloride, for example, and a suitableoil are used, we ordinarily prefer so to design the float and thereceptacle that the maximum level which the liquid attains duringebullition is slightly below the rim of the receptacle. In this case asthe bubbles formed by the gasified refrigerant rise through the body ofliquid and emerge from the surface thereof they form a mass of bubblesor foam which builds up in height until it rises above the rim of thereceptacle, whereupon some of it is carried over into the receptacle anddrawn back to the compressor in the manner described above. In thismanner there is passed over the rim of the receptacle liquid whichconsists chiefly of the liquid forming the walls of the bubbles andwhich is practically all lubricant since the liquid refrigerant does nothave sufiicient viscosity and surface tension to form the walls of thebubbles breaking through the surface of the liquid in the mannerdescribed. In other words the formation of the bubbles incident to theevaporation appears to have a selective effect on the oil with itsresultant separation from the mass of the liquid. Furthermore.

any slight amount of liquid refrigerant that may be dissolved in thelubricant forming the foam has ample opportunity to evaporate 'before itenters the float and is drawn out through the suction tube 24.

It is to be understood that the apparatus can be operated in the mannerlast described with the maximum liquid level below the rim of thereceptacle when sulphur dioxide and oil are employed as well as whenrefrigerants such as methyl chloride or ethyl chloride are employed;indeed we ordinarily prefer to sooperate the apparatus regardless of therefrigerant used when the bath of liquid refrigerant in the evaporatoris relatively shal- 7' low, since in such cases, the momentary rise ofthe liquid level at the beginning ofthe evaporation is not greatly abovethe level maintained as the evaporation continues.

.A variation of the above described operation that occurs under someconditions is to be noted. That is to say, where a refrigerant isemployed in which the lubricant has a limited solubility, andparticularly when active evaporation is not going on, bubbles from timeto time rise through the liquid in theevaporator and burst through thesurface of the liquid with more or less explosive force and projectsmall quantities of lubricant upward from the said surface. Some of the35 lubricant thus thrown up from the surface of the bath falls over intothe 'wide opening afforded by the receptacle and thus finds its way backto the compressor.

It will be observed that the refrigerant evaporated from the body ofliquid in the evaporator, in being drawn from the evaporator, firstpasses over the rim of the receptacle and into the latter, whenceit iswit-h drawn through the tube 24 and suction conduit 8. It thus appearsthat the rim of the receptacle constitutes what may be considered theprimary inlet opening of the discharge passage of the evaporator. Sincethe receptacle rim has a very long perimeter, in com-' parison with thecircumference of the discharge tube 24, the velocity of the gas flowingover the rim and into the receptacle is relatively low. This featureobviates entrainment by the gas of the boiling liquid which attainslevels nearly up to the rim of the receptacle. Such entraining effectsof a streamof gas upon a liquid are quite marked where the velocity ofthe gas is high, as is evidenced by the fact that the action of the gasentering the lower end of the tube 24 at relatively high velocity is tokeep the receptacle practically completely empty of liquidnotwithstanding the fact that the lower end of the tube 24 issubstantially above the. bottom of the receptacle. It is obvious thatthe long perimeter of the receptacle rim makes it possible for arelatively large amount of lubricant to flow into the receptacle quicklyeven if the level of the lubricant is raised but a little above therim.The large area of the top opening of the receptacle, furthermore,presents ample opportunity for the lubricant thrown up by bubblesbreaking through the surface of the liquid to fall into the receptaclein a manner previously described.

In Figs. 4 and 5 we have shown a modified form of the evaporator of thesystem. In this latter construction there is an evaporator shell 29somewhat oval or elliptical in horizontal section, as indicated in Fig.5.. The lower part of this evaporator projects downward through the topwall of a brine tank which is of the same character as the brine tank ofthe first. described evaporator. The top wall of the evaporator shell isprovided with a fitting 31 into which is screwed a depending tubefitting 32 which carries a needle valve 33 at its lower end and servesto guide the inverted cup float 34. The parts 32, 33 and 34 andadditional immediately associated parts shown in Fig. 4 being like thecorresponding parts of the evaporator shown in Fig. 2. The fitting 32 isadapted to connect with the'liquid refrigerant supply pipe 10 of thesystem. In this last construction, however, there is an open toppedreceptacle 35 in the evaporator difiering from the relit) ceptacle inthe first described evaporator. The receptacle35 in the secondevaporator has a bottom wall 35" and an upstanding side wall 35 which iscurved to conform to the adjacent wall of the float 34. At its oppositeedge the bottom wall 35 is attached to the side wall of the shell 29 sothat the latter in effect constitutes a side wall for the receptacle 35,the latter beingcrescent shaped in horizontal section, as shown in Fig.5. The side wall of the shell 29 is then apertured to receive a pipefitting 36 which is adapted to be connected with the suction conduit 8of the system. The fitting 36 affords a discharge outlet for thereceptacle 35 at the bottom thereof through which liquid can flow bygravity if the evaporator is disposed at the highest point of therefrigerant circulating system, as shown in Fig. 1.

The operation of the evaporator shown in Figs. 4: and 5 is the same asthe operation of 5 the evaporator shown in Figs. 2 and 3, ex-

cept that the liquid lubricant which is separated from the liquid massin the evaporator and delivered into the receptacle 35 can run freely bygravity into the suction return line 8 of the system. Accordingly theoperation of the last described construction will be understood withoutfurther description.

From what has been said in the foregoing description it will be apparentthat the height to which the side wall of the lubricant receptor shouldrise abovethe normal, quiescent level of the liquid in the evaporator inorder to insure separation of the lubricant from the liquid refrigerantand discharge of the sepa rated lubricantfrom the evaporator, must bedetermined, in the design of any specific apparatus, in relation toother factors which will vary for different designs. As noted earlier inthe description, such factors include particularly the relative depth ofthe liquid refrigerant in the evaporator and the heat load (rate of heattransfer) to be .carried' by the evaporator. The heat load, in turn,depends upon the size or area of the evaporator walls contacted by theliquid refrigerant,

the capacity of the compressor, etc. When the heat load is to be widelyvariable, the maximum rate of heat transfer is, of course, to be takeninto account in determining the height of the receptor walls, as well asthe proportions of other parts of the evaporator structure. Suchconsiderations will enable the designer to estimate roughly the heightof the receptor wall for any specific apparatus and if, on trial of theapparatus, such height proves too great or too small to effect thedesired separation and discharge of lubricant, it can be altered to givethe desired result. In such trial of a newly designed evaporator thefunctioning of the oil return can readily be checked by making a shortsection of the evaporator discharge line of suitable glass tubing, thepassage of oil or of mixed oil and liquid refrigerant being clearlyvisible and distinguishable through the glass wall of the tube.

It is to be observed that the mechanical agitation of the liquid in theevaporator during evaporation, particularly in the uppermost stratum ofthe liquid, varies with the amount of oil in the liquid, the mechanicalagitation due to the bubbling being greater when the proportion of oilpresent is greater. Thus,

there is in effect an automatic control of the rate of discharge oflubricant from the evaporator, because when the amount of lubricant inthe evaporator increases the resultant increase in the mechanicalagitation due to theebullition increases the rate at which the mass ofbubbles or foam consisting of lubricant and gas forms and builds up fromthe surface of the liquid and, consequently, the rate at which excesslubricant is discharged into the recep-.

tacle. Our improved method of separating the lubricant from therefrigerant in the evaporator and discharging it from the evaporator tobe returned to the compressor, by taking advantage of the inherentvariation in the rate of foam formation with varying proportions oflubricant, enables us, under all working conditions, that is, undervarying rates of heat transfer, with our improved apparatus to maintaina relatively low percent age of lubricant in the evaporator without mathe evaporator along with the lubricant.

risk of discharging liquid refrigerant from This is true both in thecase of refrigerants,

such as sulphur dioxide, in which lubricant is partially soluble andalso in the case of refrigerants, such as methyl chloride and ethylchloride, in which the lubricant is more high-v ly or completelysoluble. This is a matter of I V importance.

very considerable practical Thus, when a refrigerant such as sulphurdioxide is used we are enabled to operate the evaporator with arelatively thin stratum of lubricant on the refrigerant and largelyavoid the difficulty incident to a thick stratum of lubricant, namely,that the theoretical pressure-temperature relation of the refrigerantmethyl chloride, in which the lubricant is cal pressure-temperaturerelations'of .the refrigerant in setting the pressure operated switchwhich controls the operation of the compressor to maintain the desiredtemperature in the evaporator. Furthermore. the very fact that ourimproved method and apparatus maintains a lower concentration oflubricant in the refrigerant lowers the varia-- tion of theconcentration, thus rendering the pressure-temperature relation of theliquid in the evaporator more constant. Similarly, when use is made-ofrefrigerants, such as fully soluble, the low concentration of lubricantwhich we are able to maintain in the evaporator avoids the diilicultyincident to high concentration of lubricant that the latter raises theboiling point of the refrigerant and correspondingly reduces thecapacity and efficiency of the compressor. Furthermore, as in the caseof a refrigerant such as sulphur dioxide, the fact that a lowconcentration of lubricant is maintained lowers the variation ofconcentration and makes possible more uniform pressure-temperaturerelations for the liquid in the evaporator.

. Our improved type of float has the marked advantage that its buoyancyis aifected to a minimum extent by variations in the specific gravity ofthe liquid in which it is partially submerged. This is due to'the factthat the float has upright cylindrical sides so that when the specificgravity of the liquid is reduced by the ebullition the increased depthof the submergence of the float causes a larger increase in thedisplacement,to compensate for the lower specific gravity of the liquid,than could be secured with a previously used spherical or horizontalcylindrical float normally submerged to its median plane. Furthermore,our unproved form of float has rel- -atively great buoyancy and liftingpower.

This is due to several things. It is due in part to the fact that thefloat is immersed partly in gas and partly in liquid, that is to say, intwo fluids of widely different specific gravities, whereas in the caseof the closed floats of spherical or horizontalcylindrical formheretofore commonly used in V flooded evaporators for controlling thelevel thereon, the specific of the liquid sulphur dioxide refrigerantupon which the excess lubricant floats, the float has been immersedwholly in liquid, that is, partly inthe liquid sulphur dioxide andpartly in the stratum of oil floating ravities of these two 1i uidsdiflering relatively little-from each other. The relatively greatbuoyancy of our float is further due to the fact that the float can havea large displacement volume and yet be relatively light in weight. Thisis'possible because the float is open and its walls are never subjected,as are closed floats, to unbalanced gas pressures in the evaporator, sothat the walls can be made of relatively thin metal. This is a matter ofconsiderable im portance when it is considered that the gas pressures insuch evaporators vary all'the way from about 14 pounds below atmosphericpressure when the s stem is being exhausted preparatory to c arging withrefrigerant, upward to about 100- pounds above atmospheric pressure whenthe evaporator is subjected to summer temperatures during shipment.

.It is obvious that our improved form of float can be fabricated with aminimum expense for material and labor.

The float valve also is exceedingly simple in construction and reliablein operation. It will be observed that the depending inlet tube, thefloat valve carried by the lower end of the said tube and the filterwhich in turn is carried by the body of the valve, are assembled as aunit and can with the greatest ease be inserted into and removed fromthe evaporator shell as a unit. This very greatly facilitates theservicing of the evaporator. The fact that with our improved form ofconstruction the float has no positive connection with the needle valve,as by links, levers or the like, both reduces the cost of producing theparts, facilitates their assembly, and minimizes wear and tear and thecorresponding troubles in operation. However it is to be observed thatinsofar as some of the broader aspects of the float construction areconcerned, the invention is not limited to a construction in which thefloat actuates the valve directly without the interposition of an arm orlever.

In connect-ion with the foregoing description and certain of the claimsit will be understood that in characterizing the receptacle in theevaporator as having a top opening of large area or relatively longhorizontal perimeter, those terms are employed in comparison with therefrigerant discharge openings of prior evaporators, which have commonlybeen comparable in size to the refrigerant discharge or suction ductand, of course, the terms are used with regard to the previouslyexplained functions performed by the large primary inlet of thedischarge conduit, as well as the obvious function of readily andeffectively receiving the lubricant lifted, in the ways above described,by evaporation occurring in the body of refrigerant.

In the foregoing description and in the drawings, we have presented twoof the preferred forms of embodiment of our invention, but, from whathas been said, it will be obvious that the embodiment of our improveanddeliver the liquefied refrigerant tothe' evaporator to withdrawrefrigerant ments may vary widely within the scope of our invention asdefined in'the appended claims. For example, it is obvious that thereceptacle provided in the evaporator may take a wide variety of formsand may be fixed in position in a great variety of ways. It is alsoclear, insofar as some of the broader aspects of the invention areconcerned, that any suitable means whatsoever may be provided formaintaining the normal level of the body of refrigerant in theevaporator,

What we claim is: v

1. In refrigerating apparatus, the combination of an evaporator of theflooded type; a compressor having its inlet connected to the evaporatorto wlthdraw refrigerant gas "therefrom; a condenser connected to receivecompressed refrigerant from the compressor evaporator; a body ofrefrigerant in 'the closed system; liquid lubricant in the closed systemof lower specific gravity than the liquid refrigerant and soluble to alimited extent in the latter; means for intermittently driving thecompressor; a receptacle secured in fixed position in the evaporator andhaving an inlet for lubricant and refrigerant gas of relatively longhorizontal perimeter; a discharge duct leading from the said receptacleto the suction conduit of the compressor; and means associated with theevaporator for controlling admission thereto of the liquid refrigerantand maintaining in the evaporator a normal liquid level at a distancebelow the said inlet of the receptacle such that the intermittent riseof said level when'the compressor is intermittently started causesdischarge into the receptacle of liquid lubricant from the top of thebody of liquid in the evap- '1 orator without such discharge of liquidrefrigerant.

2. In refrigerating apparatus, the combination of anevaporator of theflooded type; a compressor having its inlet connected to the astherefrom; a condenser connected to receive compressed refrigerant fromthe compressor and deliver the li uefied refrigerant to the evaporator;a ho y of refrigerant in the closed system; liquid lubricant in theclosed system of lower specific gravity than the liquid refrigerant andsoluble'to a limited extent in the latter; means for intermittentlydriving the compressor; a receptacle secured in fixed position in theevaporator an having an inlet for lubricant and refrigerant gas ofrelatively long horizontal perimeter; a discharge duct leading from thesaid receptacle to the suction conduitof the. compressor, said ducthaving its inlet disposed at a point relatively remote fromithe boundaryof the said inlet of the said receptacle; and means associated with thevaporizer for controlling the admission thereto of liquid refrigerantand maintaining in. the evaporatora normal liqthe receptacle such thatthe intermittent rise -uid level at a distance below the said inlet ofof said level when thecompressor is intermittently started causesdischarge into the receptacle of liquid lubricant from the top acompressor having its inlet connected to p the evaporator to withdrawrefrigerant gas therefrom; a condenser connected to receive compressedrefrigerant from the compressor and deliver the liquefied refrigerant tothe evaporator; a body' of refrigerant in the closed system; liquidlubricant in the closed system of lower specific gravity than the liquidrefrigerant and soluble to a limited extent in the latter; means forintermittently driving the compressor; a receptacle secured in fixedposition-in the evaporator and having an inlet for lubricant andrefrigerant gas of relatively long horizontal perimeter and an outletthrough which lubricant'can' flow by gravity into the connection leadingto the inlet ofuthe compressor; and means associated with the evaporatorfor controlling admission.

thereto of the liquid refrigerant and maintaming in the evaporator anormal liquid level at a distance below the said inlet of the receptaclesuch that the intermittent rise of said level when the compressor isintermittently started causes discharge into the receptacle of liquidlubricant from theto of the body of liquid in the evaporator wit outsuch discharge of liquid refrigerant. v

4. In refrigerating apparatus, the combination of an evaporator of theflooded type; a compressor having its inlet connected to the evaporatorto withdraw refrigerant gas therefrom; a condenser connected to receivecompressed refrigerant from the compressor and deliver the liquefiedrefrigerant to the evaporator; a body of refrigerant in the closedsystem; liquid lubricant in the closed system of lower specific gravitythan the liquid refrigerant and soluble to a limited extent in thelatter; means for intermittently driving the compressor; a receptaclesecured in fixed position in the evaporator and having an inlet forlubricant and refrigerant gas of relatively long horizontal perimeterand an outlet through which lubricant can flow by gravity into theconnection leading to the inlet of the compressor, the said outlet beingdisposed at a point relatively remote from the boundary of the saidinlet of r the said receptacle and means associated with the vaporizerfor controlling admission thereto of liquid refrigerant and maintainingin the evaporator a normal liquid level at a distance below the saidinlet of the receptacle such that thecintermittent rise of said levelwhen the compressor is intermittently started causes discharge into thereceptacle of liquid lubricant from the top of the body of liquid in theevaporator without such discharge of liquid refrigerant.

5. In a' refrigerant evaporator of the flooded type adapted for use inrefrigerating systems in which the working parts of the apparatus arelubricated by liquid lubricant that is of lower specific gravity thanthe liquid refrigerant and'soluble to at least some extent in the liquidrefrigerant, the combination of an evaporator casing having an inlet forliquid refrigerant and an outlet for gaseous refrigerant adapted'to-beconnected with the suction side of a/refrigerant compressor; areceptacle secured in fixed position in the evaporator and having a topopening of large area and an outlet through the outlet of the evaporatorcasing, the said receptacle being disposed in relation-to the outlet ofthe evaporator casing so that lubricant can flow by gravity from thereceptacle through the said outlet; and means for controlling admissionof liquid refrigerant to the casing and maintaining therein a normalliquid level at such a distance below the top opening of the saidreceptacle that when lubricant in the casing is lifted by ebullitionfrom the body of liquid therein it will fall into the saidreceptacleseparate from the liquid refrigerant in the evaporator.

6. In a refrigerant evaporator of the flooded type adapted for use inrefrigerating systems in which the working parts of the apparatus arelubricated by liquid lubricant that is of lower specific gravity thanthe liquid refrigerant and soluble to at least some extent in the liquidrefrigerant, the combination of an evaporator casing having an inlet forliquid refrigerant and an outlet for gaseous refrigerant adapted to beconnected with the suction side of a refrigerant compressor; areceptacle secured in fixed position in the evaporator and having atopopening of large area and an outlet through the outlet passage of theevaporator casing, said outlet being disposed at a point remote from theboundary of the said top opening of the receptacle and said receptaclebeing disposed inrelation to the outlet opening of the casing so thatlubricant can flow by gravity from the receptacle through the saidoutlet; and means for controlling admission of liquid refrigerant to thecasing and maintaining therein a normal liquid level at such a distancebelow the top opening of the said receptacle that when lubricant in thecasingis lifted by ebullition from the body of liquid therein it willfall into the said receptacle separate from the liquid refrigerant inthe evaporator.

7. In refrigerating apparatus; the com' bination of an evaporator of theflooded type; a compressor having its inlet connected to the evaporatorto withdraw refrigerant as therefrom; a condenser connected to recelvecompressed refrigerant from the compressor and deliver the liquefiedrefrigerant to the evaporator; a body of refrigerant in the closedsystem; liquid lubricant in the closed system of lower specific gravitythan the liquid refrigerant and soluble to at least some extent in thelatter; means for intermittently driving the compressor; a receptaclesecured in fixed position in the evaporator and having an inlet forlubricant and refrigerant gas; a discharge duct leading from the saidreceptacle to the suction conduit of the compressor; and meansassociated with the evaporator for controlling admission thereto of theliquid refrigerant and maintaining in the evaporator a normal liquidlevel at a distance below the said inlet of the receptacle such that theintermittent lifting of lubricant above said normal level incident toevaporation in the body of refrigerant when the compressor isintermittently started causes dis- 8; charge into the receptacle ofexcess lubricant without such discharge of liquid refrigerant.

8. In refrigerating apparatus, the combination of an evaporator of theflooded type; a compressor having its inlet connected to the evaporatorto withdraw refrigerant gas therefrom; a condenser connected to recelvecompressed refrigerant from the compressor and deliver the liquefiedrefrigerant to the evaporator; a body of refrigerant in the closedsystem; liquid lubricant in the closed system of lower specific gravitythan the liquid refrigerant and soluble to at least some extent in thelatter; means for intermittently driving the compressor; a receptaclesecured 123 in fixed position in the evaporator and having an inletforlubricant and refrigerant gas 0 relatively larger areas; a dischargeduct leading from the said receptacle to the suction conduit of thecompressor, said duct having its inlet disposed at a point relativelyremote from the boundary of the said inlet of the said receptacle; andmeans associated with the vaporizer for controlling the admissionthereto of liquid refrigerant and maintaining in 11,; the evaporator anormal liquid level at a distance below the said inlet of the receptaclesuch that the intermittent lifting of lubricant above said normal levelincident to evaporation in the body of refrigerant when the com- 3';pressor is intermittently started causes discharge into the receptacleof excess lubricant without such discharge of liquid refrigerant.

In testimony whereof, we hereunto aflix our signatures.

HERBERT C. KELLOGG. EDWARD M. MAY.

GERTIFIGA'IFE 0F CGRERECTWN.

Patent No. i,885,837. November i, 1932.

HERBERT C. KELLOGG ET AL.

it is hereby certified that errm appears in the printed specification ofthe above numbered patent requiring correction as follows: Page 8, line103, eiaim 8, for "larger areas" read "large area; and that the saidLetters Patent should he read with this correction therein that the samemay eonterm to the record of the ease in the Patent Utiice.

Signed and sealed this 10th day eiianuary, A. D. 1933. f

hi i. re, (Seat) Acting Commissioner 0t Patents.

